The specification of my European Patent No. 0086606 discloses a flexible guard suitable for location around a power take-off (PTO) shaft extending between a tractor and a towed accessory or implement. Each of the ends of the flexible guard may comprise an end coupling with hook-shaped clamps which cooperate with a raised lip on the tractor or implement housing. Different tractors and different implements housings tend to have different fixing points for the attachment of connectors and therefore a range of such attachment connectors is required to provide cooperating connector portions, to enable attachments such as guards to be connected thereto.